There’s a very famous rule in business called the “80/20” rule?80 percent of all your sales will come from 20 percent of your client list. Surprisingly, it can be applied to many situations, including art. For instance, 80 percent of your art sales comes from 20 percent of your customer base.

I could have spent much more time fussing with details in the lilac bushes, and the other greenery surrounding the focal point of Make Believe. But I wanted to suggest the lilacs and focus attention on the doll on the quilt. So the doll and the quilt got the details. (In the collection of the Jewish Center for the Aged, St. Louis.)

In a similar way, 80 percent of your artmaking process is all you need. The last 20 percent is usually unnecessary fussing, which often takes away the freshness of the painting. In essence, it’s overworked because we don’t know when to stop.

So try stopping when you’re 80 percent complete. You won’t know exactly when you reach this point—you’ll have to guess—but after a couple of times you’ll get the feel of it. After you’ve stopped, prop the painting up in your home in its 80 percent condition and live with it for a few days.

And if you decide the painting really needs more work or more details, put them in. Stopping at 80 percent of completion is only an exercise—you’re the best judge of whether you’re 80 percent done or 100 percent done.

Most of Waiting is the white of the paper or the paper with a very light glaze on it. I had to control myself to not fuss with the water too much. I was tempted to put many more lines and washes in the water, but luckily I stopped myself before I did. The absence of paint and brushstrokes in this hazy scene, actually suggests more than if I had tediously painted in intricate details of water.

I frequently ask well-known artists when they know a piece is done. Often they look at me with a blank look and answer, “When it’s done, it’s done.” They either have a clear initial vision about what the final piece will look like, or they’re so experienced that they “just know.” (Or both.) You’re aiming to get to that point when you just know. I’ve found though, that I still find it helpful to stop at 80 percent. It gives me a chance to evaluate values, proportion, composition, etc. And I still have a great opportunity for making adjustments.

I’ve also applied this 80/20 guideline to another aspect of my painting: I try to make sure 20 percent of my painting is of a very strong value, either white or black. See how this 80/20 rule can work for anything?

Mary Todd Beam is a famous American artist, painter, workshop instructor, juror, lecturer and an elected member of the American Watercolor Society, the National Watercolor Society, the Society of Layerists in Multimedia, the Ohio Watercolor Society and many others. Her work was recently featured in Watercolor Magic, and her artwork and text have been featured in several books on painting, most notably Maxine Masterfield’s Painting the Spirt of Nature, Nita Leland’s The Creatve Artist and Michael Ward’s The New Spirit of Painting.